This paper is based largely on an expert assessment on mould in indoor environments carried out by the French agency for food, and environmental and occupational health and safety (ANSES), within the national Action Plan on Indoor Air Quality. The aim is to provide an overview of the knowledge of indoor mould in France, to determine the factors influencing mould in buildings from an energy perspective, and to investigate the link with regulations dealing with housing construction and refurbishment. The purpose of the assessment is, ultimately, to make recommendations as to how to reduce the presence of mould in indoor environments. The paper is the result of an analysis of different kinds of data and is not a systematic review of the existing literature on indoor mould. We used data from surveys investigating mould contamination in indoor environments in France and academic publications focusing on energy issues, fuel poverty, building material, and their consequences on mould development. The data also drew on hearings with French stakeholders and an international consultation with national agencies and authorities. The results show that visible mould is estimated to be present in between 14 and 20% of dwellings in France, a number that is largely due to the fact that old dwellings do not respect thermal and ventilation regulations and that occupants' socio-economic characteristics can lead to fuel poverty or situations of overcrowding. The lack of a specific regulatory framework concerning mould prevention and remediation in France is highlighted by the stakeholders’ answers and experience in other countries (in particular the Nordic countries). The recommendations in the article insist on coherence between thermal regulations and the risk of mould development, development of training for professionals, and control of constructions. Propositions for management strategies concerning assessment of exposure are also presented.